1. Field of the Invention
The present invention relates to a head lamp for a vehicle.
2. Description of the Related Art
Projector type or reflective type light source units (lamp units) have been used as head lamps for vehicles.
The reflective type light source unit does not include a projector lens, it includes a light source and a reflector, whereby light emitted from the light source is reflected and irradiated to a desired direction by the reflector.
The projector type light source unit includes a projector lens and a shade in addition to a light source and a reflector.
Japanese Patent No. 4563912 discloses a head lamp structure for a vehicle, in which a plurality of low-beam lamps are disposed at upper positions and at least one high-beam lamp is disposed at a lower position, and each of the low-beam lamps and the high-beam lamp is configured as a projector type.
JP-A-2010-225462 discloses a head lamp for a vehicle, in which a first low-beam part is disposed at an upper position and a second low-beam part is disposed at a lower position, each of the first low-beam part and the second low-beam part is configured as a reflective type, and a frame for holding the first low-beam part and the second low-beam part and a frame for holding a high-beam part are integrally provided.
The projector type light source unit has the following problems.
(1) The projector lens and the shade become necessary.
(2) Since the projector lens is expensive, the cost of this light source unit increases together with the effects of (1).
(3) The utilization factor of light reduces due to the optical loss caused by the projector lens.
(4) Although this light source unit is suitable for condensing and distributing light at a distant area as compared with the reflective type light source unit, this light source unit is not suitable for irradiating a wide area.
According to the technique of Japanese Patent No. 4563912, since the plurality of projector type low-beam lamps are provided in addition to that each of the low-beam lamp and the high-beam lamp is configured as the projector type, the problems (1) and (2) become more apparent.